DVA kit con unità di controllo azionamento intelligente La pompa a cilindrata costante regolabile elettronicamente di HYDAC KineSys

KineSys variable-speed drives (DVA) are the perfect example of symbiosis between hydraulics and electronics. Thanks to the integrated closed-loop control, the drive motor can be switched on and controlled according to requirements. This results in major potential for energy savings, as only the amount of energy that is actually needed is made available. This means that energy savings of up to 70 % can be achieved, depending on the machine cycle. The condition-optimised adjustment of the KineSys solution reduces the power dissipation to a minimum. It also drastically reduces the complexity on the hydraulic side.

Closed-loop control circuits

• A control circuit is the self-contained sequence of actions for influencing a physical variable in a technical system or other type of system.

Speed control

• If the general control circuit's system is transferred to the control types used in hydraulics, the following block diagram for speed control is obtained.
• The difference between the target value and actual speed is transferred to the frequency inverter. This then controls the motor so that the control difference (in our example, the speed deviation) is as close to zero as possible.

Pressure control

• This analogy can also be applied to pressure control. The target and actual pressure difference determines the control of the motor. The actual physical pressure variable is determined by a sensor within the fluid and in turn serves as a reference variable for the controller.

Accumulator charging mode

• The accumulator charging mode is a special pressure control application. The underlying controller structure is identical to the figure above.
• If the desired target pressure is reached and there is no decrease in hydraulic power, the drive runs at minimum speed to ensure continuous lubrication of the hydraulic pump. After an adjustable period of time (ΔTimeHysteresis), the drive is switched off completely. If the actual measured pressure value falls below the difference between the target pressure value and ΔPressure hysteresis, the drive switches back on and automatically switches to pressure control. The greatest possible energy savings can be achieved with this operating mode.

Parameterisation

Parameterisation means providing a program with variables that control the process.
This also applies to the parameterisation function of our drive controllers. The various parameters are used to define functional variables such as:

• Minimum and maximum speeds
• Control types
• Processing digital and analogue input and output signals
• Bus system interfaces
  etc.

Standard parameterisations

With our many years of experience with a wide variety of applications, we have defined standards that fully cover most use cases. Adaptations to your system are of course taken into account for every product that we deliver. 

Speed control

Below you will find the most important parameters that are present when a drive controller with speed control is supplied to a customer.

• Customer speed target value on analogue input 2
• Analogue input 1 for pressure sensor (no effect on speed control)
• Drive enabling via digital input 1
• Acknowledgement of pending errors via digital input 4

Pressure control

Below you will find the most important parameters that are present when a drive controller with pressure control is supplied to a customer.

• PID process controller for pressure control
• Specification of the P and I components of the controller
• Target value specification by the customer via analogue input 2
• Drive enabling via digital input 1
• Acknowledgement of pending errors via digital input 4

Accumulator charging mode

Below you will find the most important parameters that are present when a drive controller with the accumulator charging mode is supplied to a customer.

• PID process controller for pressure control
• Specification of the P and I components of the controller
• Target value specification by the customer via analogue input 2
• Drive enabling via digital input 1
• Acknowledgement of pending errors via digital input 4

Accumulator charging mode

• Pressure value as actual value of the PID controller on analogue input 1 (already wired at the factory)
• Standby time = switch-off time after reaching the target pressure + minimum speed
• Standby hysteresis = switch-on and switch-off thresholds in relation to the target pressure

Optional fieldbus system

If the drive controller is ordered from KineSys with the "Fieldbus" option, the following process data is provided for reading and writing as standard. Further information can be found in the documentation for the particular bus system.
 

Circuit diagram

The two circuit diagrams for motor-mounted frequency inverters from KineSys with and without the STO function (Safe-Torque-Off) are shown below. Controlling a valve via digital output and an optocoupler is an option and is not included in the standard scope of delivery.

Circuit diagram with STO function – download now

Circuit diagram without STO function – download now